leetcode 110 Balanced Binary Tree

Given a binary tree, determine if it is height-balanced.

For this problem, a height-balanced binary tree is defined as a binary tree in which the depth of the two subtrees of every node never differ by more than 1.

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class Solution {
public:
int balanced(TreeNode *root) {
if(root==NULL) {
return 0;
}

int left = balanced(root->left);
if(left==-1) return -1;

int right = balanced(root->right);
if(right==-1) return -1;

if(abs(left-right) > 1) return -1;
return max(left, right)+1;
}
bool isBalanced(TreeNode *root) {
if(root == NULL) return true;

int h = balanced(root);

return h!=-1;
}
}